Thermal Radiant Barrier for Use in Roof Insulation

ABSTRACT

A thermal radiant barrier and methods of use are provided. The thermal radiant barrier includes a first elongated planar member and first and second walls projecting from opposite edges of the planar base. When in use, the thermal radiant base is affixed to the underside of roof decking with the first and second walls being affixed to the underside of the decking. An air passageway from the soffit vent along side the underside of the decking is created to permit the air to be channeled from the soffitt vent into the attic area alongside the decking. The temperature of the air is controlled by using material of an R-value recommended by the construction code of the region. The thermal radiant barrier may include a second elongated planar member hingeably connected to the first elongated planar member at an angle equal to the angel between the rafter and joist in a roofing structure. The second elongated member is positioned underlying Batt insulation in proximity to the soffitt vent and soffitt baffle. The second elongated member has an R-value recommended in the geographic location. In use, the R-value at an area of compressed insulation is given by the R-value of the second elongated member.

FIELD OF INVENTION

This invention relates to pitched roof insulation. Particularly, theinvention relates to the elimination of ice dams conditions.

BACKGROUND

Ice dams are formed when heat from the inside of a home escapes into theattic and warms the roof decking during the winter. FIG. 1 brieflyillustrates the cross-section of an exemplary pitched roofing structure100 that may be found in the prior art. Roofing structure 100 includes adecking 102 supported by rafter 104. A bottom most portion of rafter 104is ordinarily affixed to an end portion of a joist 106. In proximity tothe bottom most portion of rafter 104 and the end portion of joist 106is an eaves 108, extending outwardly from an outer support wall 110toward the underside of decking 102. Positioned in the eaves 108 is asoffit vent 112 which Permits air outside the roofing structureillustrated by air cloud 114 (“outside air 114”) having a temperaturet_(o) to enter through soffit vent 112 into the attic area.

FIG. 2 is a frontal view of the underside, of roof structure 100 as seenfrom the perspective of one positioned in the attic space of a dwelling.Roofing structure 100 includes multiple roof rafters (i.e., multiplerafters 104) supporting decking 102. Rafters 104 may be regularly spacedone from another, for example by a distance d_(r). Distance d_(r) may bechosen based on, for example, joist material, size, and environmentalconditions. Distance dr is usually recommended by the building codeauthority of the geographic region.

As shown in FIG. 1 and FIG. 2, the outside air 114 enters through soffitvent 112 into the attic space to mix with attic air illustrated by cloud116 (“attic air 116”) having a temperature t_(e). Ice dams are createdwhen the temperature t_(e) combines with temperature t_(o) therebyheating and melting snow on the outer side of decking 102. The meltedsnow then runs from the outer decking to the eaves 108 where itrefreezes. The continual thaw and re-freeze process creates the icedams. The result is water backing up under the roof shingles or behindfascia boards where it can soak through the roof decking or wallsheathing, causing damage to attics, ceilings and walls. Uncheckedmoisture can promote mold, mildew, and wood rot.

Ice dams can be prevented by keeping the difference in temperature ofthe attic air t_(a) and the outside air t_(o) as near to zero aspossible. The mixing of the outside air 114 with the attic air 116 inthe attic space tends to stabilize the temperature of the resultingmixed air in the attic space to near t_(o)+t_(a). However, thetemperature rising from the living space of a dwelling through the atticfloor into the attic space works against the stabilizing affect of themixing process. The heat of temperature t_(l) enters from the livingspace into the attic space through the attic floor 122. This livingspace heat of temperature t_(l) tends to raise the temperature of theattic space t_(a) to a temperature t_(a)+l_(h) which further promotesthe melting and refreezing condition noted above.

Attic floor insulation 118 (i.e., Batt insulation) is added to preventheat t_(l) from the living space (i.e. “living area”) of the homeescaping into the attic raising the attic air temperature above thetemperature of the outside air. Attic floor insulation 118 is ordinarilyused to retard the flow of heat from the living space into the atticspace. To ensure proper effective placement, the attic insulation 118 isordinarily placed between joists 106 as close to soffit vent 112 aspossible without obstructing the circulation of the outside air throughthe soffit vent 112 into the attic space. Insulation baffles 120 areused to ensure that soffit vent 112 remain unobstructed by the atticinsulation 118.

One clear limitation to merely insulating the attic floor 122 is thatthe attic insulation merely retards the transference of heat t_(l) fromthe living space into the attic space. Heat still rises through theinsulation 118. The ability of the attic insulation 118 to retard theheat transference is measured in resistance values (R-value). InsulationR-values are generally recommended by geographic zones. The higher theR-value, the greater the insulating power. For example, attic insulation118 is ordinarily relegated to an average R-value of R38. Further still,the geographic zones may be organized by climate. Alternatively,geographic zones may be building or construction zones recognized by thebuilding authority establishing the relevant R-value

Traditional roofing systems 100 have problems not addressed in the priorart. For example, attic insulation 118 is typically unrolled betweenjoists 106 to soffit vent 112 to abut up against baffle 120. The atticinsulation 118 nearest the baffle 120 is typically compressed(compressed insulation 124) as is shown in FIG. 1. When the atticinsulation 118 nearest the baffles 120 is compressed the R-Value at thecompressed insulation 124 is less that the R-value of the uncompressedportion of the insulation 118. This is because R-Value is a function ofthe thickness of the insulation and the material chosen. The compressedinsulation portion permits the temperature t_(l) of the living space totransfer, more readily to the attic space. Temperature t_(l) raises thetemperature of t_(a) creating ice dam conditions. Additionally, at thecompressed insulation 124, a portion of the outside air 114 thattraverses form the soffitt vent 112 escapes around the baffle 120 suchthat it gets trapped by the compressed insulation 124. The trapped airin the compressed insulation 124 then condenses and freezes causing iceformation at the soffitt vent 112.

Further, since insulation merely retards the transference of heat fromthe living area, the temperature of the attic air t₈ is typically higherthan t_(o) by a factor of t_(l), the amount transferring thorough theinsulation. The result is that the temperature of the attic air t_(a),especially against the underside of decking 102, is higher than thetemperature of the outside air t_(o) promoting ice dam conditions.

What is needed is an article and method that ensures that even if theattic insulation near the baffles is compressed, the R-value inproximity to the compressed insulation remains at the recommendedR-value of the geographic region.

What is additionally needed is an article or method that ensures thatthe air temperature on the underside of decking is kept near thetemperature of the outside air t_(o), so that ice damming conditions maybe prevented. U.S. Pat. No. 5,341,612, issued Aug. 30, 1994 to Robbins,titled “Baffle Vent Structure” attempts to address this problem, butfalls short. For example, the baffle vent structure disclosed isfabricated of extruded polystyrene foam material without concern for therestrictive value of the polystyrene foam material chosen. As such, theair the baffle directs against the underside of the decking continues tobe adversely affected by the higher temperature of the attic area.Particularly, the air between the baffle and the underside of thedecking is higher by an at least a portion of the temperature t_(a).

SUMMARY OF INVENTION

In accordance with one embodiment of the present invention, a thermalradiant barrier for use in roof insulation is provided. The thermalradiant barrier according to the present invention is of the R-valuerequired by the geographic region. A first portion of the thermalradiant barrier of the invention is formed to fit in between furthercontrols the temperature of the air under a roof decking by channelingair from outside the roofing structure underneath the decking. Theinvention channels air from the soffit vent to the underside of the roofdecking.

The thermal radiant barrier of the present invention may further includea second portion connected to the first portion at a first end such thatthe first and second portions are in a hinged arrangement. The thermalradiant barrier second portion is of substantially similar shape and thefirst portion. The second portion is formed to fit in between floorjoists underlying the roof's ordinary Batt insulation. The area wherethe first portion and the second portion of the thermal radiant barrierare hinged is positioned abutting a soffitt vent. In this way, thesecond portion of the thermal radiant barrier ensures that the R-valueat the compressed insulation remains at the recommended R-Value for thegeographic region.

The first and second portions of the thermal radiant barrier of thepresent invention are elongated members. The first portion furtherincludes a pair of longitudinal sidewall portions, traversing the firstand second lengths of the first portion elongated member. The firstportion of the thermal radiant barrier includes a roof facing side andan attic space facing side. The longitudinal sidewalls are affixed tothe underside of the roof decking creating a passageway or channel forair to traverse from the soffit vent along the underside of the roofdecking.

In another embodiment of the present invention, the thermal radiantbarrier includes an attachment flanges for use in attaching the radiantbarrier to roof rafters.

In yet another embodiment, the thermal radiant barrier ensures that airescaping around a roof baffle is guided along the underside of the roofdecking.

In still another embodiment of the invention, the invention maintainsthe ventilating air at the temperature of the air outside the dwelling.

DRAWING FIGURES

These and other more detailed and specific features of the presentinvention are more fully disclosed in the following specification,reference being had to the accompanying drawings, in which:

FIG. 1 is a cross-sectional side view of a typical roofing system foundin the prior art.

FIG. 2 is a view of typical roofing system found in the prior art fromthe perspective of inside the attic.

FIG. 3 is a perspective view of an exemplary thermal radiant barrierfirst portion of this invention;

FIG. 4 is a front perspective view of an exemplary thermal radiantbarrier first portion of this invention in place under a roof of astructure.

FIG. 5 is a cross-sectional side view of a roofing system including thethermal radiant barrier first portion of the present invention in use.

FIG. 6 is a perspective view of an exemplary thermal radiant barriersecond portion elongated planar portion.

FIG. 7 is a perspective view of an exemplary thermal radiant barrierfirst and second portion in hinged arrangement.

FIG. 8 is a cross-sectional side view of a roofing system including thethermal radiant barrier first portion and second portion in use.

FIG. 9 is an alternate embodiment of an exemplary thermal radiantbarrier of this invention shown the thermal barrier walls at an obtuseangle.

FIG. 10 is an alternate embodiment of an exemplary thermal radiantbarrier of this invention shown the thermal barrier walls at an acuteangle.

FIG. 11 is another alternate embodiment of an exemplary thermal radiantbarrier of this invention in arc-like formation.

DETAILED DESCRIPTION OF THE INVENTION

The present may be described with reference to a pitched roof structure,the invention is contemplated for use with any roofing structure havingan attic space, such as for example trussed roofing structure. Indeedthe present invention is described with reference to a roof decking. Itis understood that in construction, the roof decking may underlie otherroofing materials such as for example, shingles.

FIG. 3 is a perspective view of first embodiment of an exemplary thermalradiant barrier 200 according to the present invention. Thermal radiantbarrier 200 comprises a first portion 210 having a rectangular shapedelongated planar base 202 of length l, width w and a thickness th. Asnoted, roof rafters are ordinarily regularly spaced a distance d_(r)apart one from the other. Width w is chosen to be less than distanced_(r). Length l may be chosen to be less than the length of the rafterssupporting a roof decking. For example, length l may be ¼ or ⅓ or ½ ofthe length of rafter 104. Alternatively, length l may be chosen to besubstantially equal to the length of rafters 104.

Thermal radiant barrier 200 may be formed of rigid material. Forexample, thermal radian barrier 200 may be formed of a rigid boardStyrofoam, formed cellulose, and the like. Since the R-value is afunction of the material chosen and the thickness of the material, thethickness th may be chosen with considerations of the material chosenand the R-value desired. For example, for a Styrofoam such that theR-value of thermal radiant barrier 200 is the R-value predetermined forinsulation according to the building code of a geographic region. TheR-value of thermal radiant barrier 200 is determined from composition ofthe material used in the construction of the thermal barrier 200 usingcalculations known by those skilled in the art. [Verify this]

Thermal radiant barrier 200 is further includes sidewalls 204. Sidewalls204 are joined projecting outwardly from planar base 202. Sidewalls 204may be constructed of similar or same material as planar base 202 suchthat sidewalls 204 have an R-value equal or substantially equal to theR-value of planar base 202. In one exemplary embodiment, the angle Θbetween planar base 202 and sidewalls 204 may be a substantially a rightangle. As shown in the Figures, alternate of the first portion 210embodiments of thermal radiant barrier 200, angle Θ may be obtuse (FIG.8) or acute (FIG. 9). Further still, thermal radiant barrier 200 may besubstantially arc shaped as shown in FIG. 10.

The first portion 210 of thermal barrier 200 may be composed of a singlepiece with planar base 202 and sidewalls 204 integrally formed.Alternatively, the planar base 202 and the sidewalls 204 may beconstructed of separate pieced formed so as planar base 202 andsidewalls 204 may be joined or affixed together.

FIG. 4 is a front perspective view of an exemplary embodiment of a firstportion 210 of thermal radiant barrier 200 of the present invention inuse. FIG. 5 is a cross-sectional view of the first portion 210 ofthermal radiant barrier 200 in use. As shown, first portion 210 ofthermal radiant barrier 200 is positioned between rafters 104. Firstportion 210 of thermal radiant barrier 200 may further be positionedoverlying an open end of soffit vent 112. Further still first portion210 of thermal radiant barrier 200 is positioned in communication withthe underside of decking 102. That is, first portion 210 of thermalradiant barrier 200 may be positioned against decking 102.

In one exemplary embodiment, first portion 210 includes means foraffixing thermal radiant barrier 200 to the underside of decking 102.Exemplary means for affixing may include tabs 206 (or flanges) shown inFIG. 1. Tabs 206 may be made integral to the sidewalls 204. Tabs 206 maybe made of any material suitable for permitting thermal radiant barrier200 to be affixed to decking 102. Tabs 206 may be formed to permit abuilder to affix the thermal radial barrier 200 using staples, nails orthe like. Other affixing means may be substituted for or included withtabs 206. For example, the affixing means may include a suitableadhesive placed on an edge of the thermal radiant barrier 200 contactingdecking 102 or rafters 104. In this way, thermal may be glued inposition.

In use, first portion 210 of thermal radiant barrier 200 creates an airpassageway (or chute) from soffitt vent 112. In some embodiments, firstportion 210 of the thermal radiant barrier 200 may be used in place of,or along with baffle 120. In one embodiment, first portion 210 ofthermal radiant barrier 200 may be positioned overlying baffle 120. Inthis position, first portion 210 of thermal radiant barrier 200 has theadded advantage of ensuring that any air escaping around the baffle 120is captured between the first portion 210 of thermal radiant barrier 200and the underside of decking 102 and channeled to the underside of thedecking 120.

As shown in FIGS. 4 and 5, the air passageway or air channel is formedbetween the decking 102 and the first portion 210 of thermal radiantbarrier 200 such that outside air 114 entering soffit vent 112 is guidedalong the underside of decking 102. The outside air 114 is guided alongthe length l of the thermal radiant barrier 200 and exits the passagewayto mix with the attic air 116. As the outside air 114 traverses from thesoffit vent 112 to the attic area, the outside air 114 traversesalongside the underside of decking 102. Thermal radiant barrier 200having a predetermined R-value chosen according to values outlined inthe geographic area's the building code, insulates the outside air fromthe higher temperature t_(a) of the attic air 116. In this way, thermalradiant barrier ensures that the temperature of outside air 114 nearestthe underside of the decking remains relatively unchanged at t_(o). Thisprovides an advantage over the prior art in that the temperature of theair nearest the underside of decking 102 is at or near the temperatureof the outside air 114, such that the difference in temperature betweenthe air nearest the underside of the decking 102 is at zero(t_(o)−t_(o)) or near zero. This temperature change eliminated orminimizes the thawing and freezing affect leading to ice dams.

Additionally, the thermal radiant barrier 200 at the soffit vent 112 isnot compressed as is the insulation 118, since the thermal radiantbarrier 200 is made of a rigid insulating material. Thus, the thermalradiant barrier 200 nearest the compressed insulation 118 will beprohibiting heat transference at the R-value of the thermal radiantbarrier 200. Thus thermal radiant barrier 200 ensures the area near thecompressed insulation 118 is kept at the R-value recommended for thegeographic region.

FIG. 7 is a depiction of an alternate exemplary embodiment of thermalradiant barrier 200 having a second portion 260, shown in FIG. 6.Thermal radiant barrier second portion 260 has a substantially elongatedand planar base 262. The second portion 260 may include a length l,width w, and a thickness th, where the length, width and thickness areequal to those same dimensions as the first portion of the thermalradiant barrier 210 depicted in FIG. 3. Second portion 260 is comprisedof a rigid insulating material as is described with respect to thermalradiant barrier 200 depicted in FIG. 3, above. Alternatively, thedimensions of second portion 260 may be such that second portion 260 maybe positioned between joist 106. In this instance, the width of secondportion 260 may be substantially equal to the distance between regularlyspaced joist 106.

FIG. 7 depicts the first and second portions of thermal radiant barrier200 in hinged arrangement. First and second portions of thermal radiantbarrier 200 may be joined at a first end of the first and secondportions by a hinging means 264, such as for example, a hinge, hingingtape, strap hinge, paper metal or plastic joint, or the like capable ofpermitting the first portion 210 of thermal radiant barrier 200 to befolded onto second portion 260. In the hinged arrangement, the firstportion 210 of the thermal radiant barrier 200 may be posited at anangle β relative to the second portion 260.

FIG. 8 shows the hinged arrangement depicted in FIG. 7 in use. As shown,the first portion 210 of thermal radiant barrier 200 is positioned as isdescribed above in FIG. 4 and FIG. 5. Particularly, the first portion210 of thermal radiant barrier 200 may be position overlying baffle 120to channel outside air 114 along the underside of decking 102.Additionally, the first portion 210 of thermal radiant barrier 200 ishingedly affixed to the second portion 260. The first portion 210 ofthermal radiant barrier 200 and the second portion 260 may be hinged atan angle β, where angle β is substantially equal to the angle drawnbetween the rafters 104 and joist 106.

The second portion 260 is positioned underlying at least portion of Battinsulation 118 and in proximity to baffle 120. In this arrangement, thecompressed insulation 124 is positioned in proximity of hinge means 262.However, as noted, the second portion 262 has an R-value recommended bythe building codes of the geographic area. In one embodiment the R-valueof the second portion 262 is substantially equal to the R-value of theinsulation 118. Since the second portion 262 is comprised of rigidinsulation it does not compress. As such, the R-value at the compressedinsulation 124 is no less that the R-value of second portion 262.Further, the second portion 260 may extend past the compressedinsulation 124 to further ensure that the R-Value immediately past thecompressed insulation 124 is at least the R-Value of the second portion260.

An additional advantage of hinged arrangement in FIG. 7 is that thearrangement additionally assists in ensuring that the air transgressingfrom soffitt vent 112 to the baffle 120 is captured by the first portion210 of the thermal radiant barrier 200 to be channeled along theunderside of decking 102.

FIGS. 9-11 depict different embodiments of the first portion 210 ofthermal radiant barrier 200. According to FIG. 9, angle Θ between planarbase 202 and sidewalls 202 may be obtuse. In this way, the volume ofoutside air 114 transgressing through the air passageway is contacting alarger surface area of the underside of decking 102. One advantage ofthis embodiment is that a greater surface area of decking 102 may bekept at or near temperature t_(o). FIG. 10 illustrates that angle Θ maybe an acute angle. One advantage of this embodiment is that it may befitted in a space between the rafters that are narrower that width w ofthe planar base 202. This embodiment including the acute angle Θ furtherpermits a greater volume of outside air to transgress the airpassageway.

Alternate embodiment in FIG. 11 illustrates that the overall shape ofthe first portion 210 of thermal radiant barrier 200 may be arc-shapedin cross-section. This embodiment is yet another embodiment forincreasing the volume of outside air 114 transgressing near theunderside of decking 102.

In all the embodiments shown, thermal radiant barrier 200 channelsoutside air alongside the underside of decking 102. The colder outsideair temperature t_(o) is kept at or near the temperature it had when itentered the soffit vent 112.

Although the present invention has been described in considerable detailwith reference to certain preferred embodiments thereof, otherembodiments are possible. For example, although the invention isdescribed with reference to pitched roofs, the invention is alsosuitable for trussed roofs of different shapes and arrangement. Theinvention is also applicable to shed roof shapes and any roof shapewherein ice dams may result. Additionally, the means for affixing thethermal radiant barrier may be any suitable means for affixing thebarrier to the underside of the decking. Where tab like affixing meansare used, the tab like affixing means may be multiple in number, or thetab may be a single tab positioned along the sidewalls of the invention.The fixing means may be integral to the sidewalls or made separate fromthe sidewalls. Therefore, the sprit and scope of the appended claimsshould not be limited to the description of the preferred embodimentscontained herein, but includes equivalents thereof.

Further, even though a preferred embodiment of the invention has thefirst and second portions of the thermal radiant barrier to be composedof the same material, it is contemplated that the first portion and thesecond portion of the thermal radiant barrier may be comprised ofdiffering materials. In this case, the thickness or the first portionand the thickness of the second portion may be different. It isunderstood that the thickness of the first or the second portion of thethermal radiant barrier may be chosen depending on the desired orrecommended R-value of each portion.

1. A thermal radiant barrier for use against the underside of a roof decking in between two spaced rafters, said thermal radiant barrier comprising: a. A thermal radiant barrier first portion including a substantially planar base, said substantially planar base substantially rectangular in shape; said thermal radiant barrier first portion planar base having a length l, a width w, and a thickness th, wherein the thickness th, is chosen in accordance with the material comprising the thermal radiant barrier such that said thermal radiant barrier first portion has a predetermined recommended attic insulation R-value for the geographic region, b. a first sidewall projecting at an angle Θ from a first side of said planar base, a second sidewall projecting at said angle Θ from a second side of said planar base, said first and second sidewalls positioned opposite one from the other, c. a means for affixing said first and second sidewalls to said underside of a roof decking, wherein said thermal radiant barrier forms an air passageway from a soffit vent, such that air is channeled from said soffit vent along the underside of said roof decking.
 2. A thermal radiant barrier of claim 1, wherein said two spaced rafters are spaced apart by a distance d_(r), and wherein said width w, is substantially equal to said distance d_(r).
 3. A thermal radiant barrier of claim 1, wherein said substantially planar base overlays a soffitt baffle for channeling said air from said soffitt vent along the underside of said roof decking.
 4. A thermal radiant barrier of claim 1, further comprising a thermal radiant barrier second portion connected to said thermal radiant barrier first portion, said thermal radiant barrier second portion including a substantially planar base substantially rectangular in shape.
 5. A thermal radiant barrier of claim 4, wherein said thermal radiant barrier first portion is connected to said thermal radiant barrier second portion by hingeable means.
 6. A thermal radiant barrier of claim 5, wherein said thermal radiant barrier second portion planer base includes length, a width, and a thickness, wherein said thermal radiant barrier second portion length and width are substantially equal to said thermal radiant barrier first portion length and width.
 7. A thermal radiant barrier of claim 6, wherein said thermal radiant barrier second portion thickness is chosen for thermal radiant barrier second portion to have a predetermined recommended attic insulation R-value for the geographic region.
 8. A thermal radiant barrier of claim 7, wherein said thermal radiant barrier second portion underlies a compressed portion of an attic floor insulation.
 9. A thermal radiant barrier of claim 8, wherein said compressed portion has an R-value less than recommended for attic floor insulation in the geographic area.
 10. A thermal radiant barrier of claim 8, wherein said thermal radiant barrier second portion underlies a portion of attic floor insulation, where said thermal radiant barrier second portion underlies an uncompressed portion of said attic floor insulation.
 11. A method for controlling the temperature of air on the underside of roof decking comprising: providing a passageway for air entering an attic through a soffit vent, said passageway for channeling said air along the underside of said roof decking, and wherein said passageway is formed of a material having an R-value recommended for attic insulation in the geographic region.
 12. A method of claim 11 further comprising providing a material under a compressed portion of an attic floor insulation, wherein said material has an R-value recommended in the geographic region for attic floor insulation. 